A method for evaluating neutron irradiation embrittlement of a metal material based on ion irradiation

Abstract

This invention discloses a method for assessing neutron irradiation embrittlement of metallic materials based on ion irradiation, comprising: S1, preparing hardness test specimens, tensile test specimens, and Charpy impact test specimens; S2, subjecting the hardness test specimens, tensile test specimens, and Charpy impact test specimens to neutron irradiation, and subjecting the hardness test specimens to heavy ion irradiation, determining the irradiation damage amount and irradiation damage rate; S3, calculating the first yield strength increment after neutron irradiation and the second yield strength increment after heavy ion irradiation; obtaining the third yield strength increment and the irradiation embrittlement transition temperature increment; S4, establishing a first relationship between the first yield strength increment and the neutron irradiation damage amount, a second relationship between the second yield strength increment and the heavy ion irradiation damage amount, and a third relationship between the third yield strength increment and the irradiation embrittlement transition temperature increment; S5, establishing an irradiation embrittlement correlation formula and calculating the irradiation embrittlement transition temperature increment value. This invention achieves accurate assessment of the irradiation embrittlement risk of metallic materials.

Description

Technical Field

[0001] This invention relates to the field of radiation damage assessment technology for metallic materials, and in particular to an assessment method for neutron irradiation embrittlement of metallic materials based on ion irradiation. Background Technology

[0002] The reactor pressure vessel (RPV) is the core pressure-bearing component of a nuclear power plant reactor, and its structural integrity plays a decisive role in the safe operation of the reactor. During long-term service, RPV steel is continuously irradiated by high-energy fast neutrons, which leads to a large number of irradiation defects inside the material, causing irradiation embrittlement and seriously threatening the service safety of the pressure vessel.

[0003] Currently, the main method for evaluating the irradiation embrittlement properties of RPV steel (described by the embrittlement transition temperature increment ΔT) is based on Charpy impact performance tests of in-reactor irradiation monitoring specimens or experimental reactor irradiation specimens. However, these methods have significant limitations: First, the number of in-reactor irradiation monitoring specimens is extremely limited (only 4 to 6 groups), making it difficult to cover the irradiation embrittlement assessment needs during extended service life (40 to 60 years, or even 60 to 80 years); second, the irradiation test cycle for experimental reactors is extremely long, typically requiring continuous irradiation for months or even years to achieve the irradiation dose accumulated during actual reactor service, and there are also problems such as high experimental costs and difficulty in flexibly adjusting experimental parameters (such as irradiation temperature and dose rate) during irradiation, which limit the implementation of RPV irradiation embrittlement assessment. Therefore, traditional evaluation methods cannot meet the urgent needs for RPV irradiation embrittlement assessment in nuclear power engineering applications.

[0004] Ion irradiation is an effective method for assessing the irradiation embrittlement of RPV steel. However, existing methods for assessing neutron irradiation embrittlement based on ion irradiation still have significant shortcomings. The widely used neutron-ion correlation factor typically only uses damage dose as a key parameter, leading to large deviations when extrapolating the neutron irradiation embrittlement law of metallic materials from ion irradiation data. This makes it difficult to accurately assess the irradiation embrittlement of RPV steel and limits the practical application of this technology in engineering assessment. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for evaluating neutron irradiation embrittlement of metallic materials based on ion irradiation.

[0006] The technical solution adopted by this invention to solve its technical problem is: a method for evaluating neutron irradiation embrittlement of metallic materials based on ion irradiation, comprising the following steps: S1. The metallic materials are processed separately to prepare hardness test specimens, tensile test specimens and Charpy impact test specimens. S2. Neutron irradiation was applied to the hardness test specimens, tensile test specimens and Charpy impact test specimens, and heavy ion irradiation was applied to the hardness test specimens to determine the irradiation damage amount and irradiation damage rate. S3. Measure the hardness of the hardness test specimens before and after irradiation, and calculate the first yield strength increment after neutron irradiation and the second yield strength increment after heavy ion irradiation; conduct tensile tests on the tensile test specimens before and after irradiation to obtain the third yield strength increment after neutron irradiation; conduct Charpy impact tests on the Charpy impact test specimens before and after irradiation to obtain the irradiation embrittlement transition temperature increment after neutron irradiation. S4. Establish the first relationship between the first yield strength increment and the neutron irradiation damage amount, the second relationship between the second yield strength increment and the heavy ion irradiation damage amount, and the third relationship between the third yield strength increment and the irradiation embrittlement transition temperature increment. S5. Based on step S4, and combining the irradiation damage amount, irradiation damage rate, and average energy of recoil atoms of neutrons and heavy ions, establish the correlation formula for irradiation embrittlement, and calculate the increment value of irradiation embrittlement transition temperature according to the correlation formula.

[0007] Preferably, in step S1, the hardness sample is processed and polished. The polishing process includes rough polishing and fine polishing. Rough polishing uses 200-2000 mesh silicon carbide sandpaper, and fine polishing uses silk impregnated with diamond powder with a particle size of 0.1-0.5 μm; and / or, The roughness of both the tensile specimen and the Charpy impact specimen is less than 0.2 μm.

[0008] Preferably, in step S2, the neutron irradiation temperature is 290℃±15℃, and the neutron irradiation dose includes at least two doses, with a neutron irradiation dose of 1×10⁻⁶. 19 n / cm 2 ~1.2×10 20 n / cm 2 Neutron energy > 1 MeV; calculate the neutron irradiation damage amount and neutron irradiation damage rate of the hardness sample.

[0009] Preferably, in step S2, the heavy ion irradiation temperature is the same as the neutron irradiation temperature. The heavy ions include at least two of iron ions, carbon ions, nickel ions, and manganese ions. The irradiation dose for each heavy ion includes at least three doses, and the irradiation dose is 1 × 10⁻⁶. 13 ions / cm 2 ~1×10 18 ions / cm 2The irradiation energy of each heavy ion includes at least 10 types, with an irradiation energy ≥5MeV / u; the heavy ion irradiation damage rate and heavy ion irradiation damage amount are calculated for each heavy ion, and the irradiation damage amount of at least one heavy ion is equal to the neutron irradiation damage amount. The heavy ion irradiation damage amount is the average value of the damage amounts of heavy ions with different irradiation energies.

[0010] Preferably, in step S3, the Vickers hardness of the hardness samples before and after irradiation is measured to obtain the Vickers hardness increments after neutron irradiation and heavy ion irradiation, respectively. Then, the first yield strength increment and the second yield strength increment are calculated using equations (1) and (2), respectively. Equations (1) and (2) are expressed as follows: Δσ y1 =3.06ΔH1 (1) Δσ y2 =3.06ΔH2 (2) Where, Δσ y1 ΔH1 represents the first yield strength increment, and Δσ represents the Vickers hardness increment after neutron irradiation. y2 ΔH2 represents the second yield strength increment, and ΔH2 represents the Vickers hardness increment after heavy ion irradiation.

[0011] Preferably, in step S4, the first relation is as shown in equation (3): (3) Where, Δσ y1 ' is the first yield strength increment, A1 is the first fitting coefficient, D1 is the neutron irradiation damage, B n The power exponent of neutron irradiation damage; The second relation is shown in equation (4): (4) Where, Δσ y2 ' is the second yield strength increment, A2 is the second fitting coefficient, D2 is the heavy ion irradiation damage, B i The power exponent of the damage caused by heavy ion irradiation; The third relation is shown in equation (5): ΔT n =p×Δσ y n (5) Where, ΔT n Δσ represents the irradiation embrittlement transition temperature increment after neutron irradiation, p is the linear fitting coefficient, and Δσ is the linear embrittlement transition temperature increment. y This represents the third yield strength increment.

[0012] Preferably, step S5 includes the following sub-steps: S5.1. The power exponents of the first and second relations are uniformly corrected, and radiation hardening correlations are established by combining the first yield strength increment, the second yield strength increment, the average energy of the recoil atoms of neutrons and heavy ions, the irradiation damage rate and the irradiation damage amount. S5.2. Based on the radiation hardening correlation and the linear fitting coefficient of the third relation, establish the radiation embrittlement correlation and calculate the radiation embrittlement transition temperature increment value according to the radiation embrittlement correlation.

[0013] Preferably, step S5.1 includes the following sub-steps: S5.1.1. The power exponent is uniformly corrected using equation (6), and the first hardened correlation is established as shown in equation (7); equation (6) is expressed as follows: b=(B n +(B i 1+ B i 2+…B i x ) / x) / 2 (6) Where b is the power exponent of the unified correction, B n B is the power exponent of neutron irradiation damage. i is the power exponent of the damage caused by heavy ion irradiation, and x is the number of heavy ion species; Equation (7) is expressed as follows: Δσ y =A3×k1×D b (7) Where, Δσ y For yield strength increment, A3 is the third fitting coefficient, k1 is the first correlation factor, D is the irradiation damage amount, and b is the power exponent of the unified correction; the expression for k1 is k1=lg(C1×φ), where C1 is the first correlation coefficient and φ is the irradiation damage rate.

[0014] Preferably, step S5.1 further includes the following sub-steps: S5.1.2. Based on the first hardening correlation, calculate the first difference between the normalized yield strength increment after neutron irradiation and heavy ion irradiation. The normalized yield strength increment is Δσ. y / k1; If the first difference is ≤5, the first hardening correlation is the irradiation hardening correlation; If the first difference is >5, calculate the average atomic recoil energy of neutrons and heavy ions, and establish the second hardening correlation as shown in equation (8), the irradiation hardening correlation is the second hardening correlation. Equation (8) is expressed as follows: Δσ y =A4×k2×D b’ (8) Where, Δσ yThe yield strength increment is represented by A4, the fourth fitting coefficient is k2, the second correlation factor is D, the irradiation damage is D, and b' is the power exponent for further correction. The expression for k2 is k2 = lg(C2 × φ) × lg 1 / 2 (E×T 1 / 2 C2 is the second correlation coefficient, φ is the irradiation damage rate, E is the third correlation coefficient, and T is the third correlation coefficient. 1 / 2 The average energy of the recoil atom; Based on the second hardening correlation, the yield strength increment is normalized again to Δσ. y / k2, calculate the second difference between the normalized yield strength increment after neutron irradiation and heavy ion irradiation, and adjust the power exponent in equation (8) until the second difference is ≤5.

[0015] Preferably, the irradiation hardening correlation is the first hardening correlation, and the irradiation embrittlement correlation is shown in equation (9): ΔT=A3×p×k1×D b (9) Where ΔT is the irradiation embrittlement transition temperature increment, A3 is the third fitting coefficient, k1 is the first correlation factor, D is the irradiation damage amount, and b is the power exponent of the unified correction; the expression for k1 is k1=lg(C1×φ), where C1 is the first correlation coefficient and φ is the irradiation damage rate; or... The irradiation hardening correlation is the second hardening correlation, and the irradiation embrittlement correlation is shown in equation (10): ΔT=A4×p×k2×D b’ (10) Where ΔT is the irradiation embrittlement transition temperature increment, A4 is the fourth fitting coefficient, p is the linear fitting coefficient, k2 is the second correlation factor, D is the irradiation damage amount, and b' is the power exponent for further correction; the expression for k2 is k2=lg(C2×φ)×lg 1 / 2 (E×T 1 / 2 C2 is the second correlation coefficient, φ is the irradiation damage rate, E is the third correlation coefficient, and T is the third correlation coefficient. 1 / 2 This is the average energy of the recoil atom.

[0016] The beneficial effects of this invention are as follows: The method for assessing neutron irradiation embrittlement of metallic materials based on ion irradiation uses irradiation damage amount, irradiation damage rate, and average energy of recoil atoms as key parameters to establish a correlation between heavy ion and neutron irradiation embrittlement. This allows for the assessment or prediction of the embrittlement level of metallic materials under neutron irradiation conditions using heavy ion irradiation parameters, thereby achieving an accurate assessment of the embrittlement risk of metallic materials during service. Combining ion irradiation with neutron irradiation can significantly reduce the assessment cycle and neutron irradiation cost of metallic materials, and improve the efficiency of irradiation embrittlement assessment. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a flowchart of an evaluation method for neutron irradiation embrittlement of metallic materials based on ion irradiation in some embodiments of the present invention; Figure 2 This is an envelope curve of irradiation damage depth-irradiation damage amount for metallic materials under different ion energy combinations according to embodiments of the present invention. Figure 3 This is a graph showing the relationship between irradiation damage and yield strength increment of metallic materials after neutron irradiation and heavy ion irradiation, according to an embodiment of the present invention. Figure 4 This is a graph showing the relationship between the third yield strength increment and the irradiation embrittlement transition temperature increment in this embodiment of the invention. Figure 5 This is a double logarithmic coordinate curve of the normalized yield strength increment versus the irradiation damage amount in an embodiment of the present invention; Figure 6 This is a double logarithmic coordinate curve of the renormalized yield strength increment and irradiation damage amount according to an embodiment of the present invention; Figure 7 These are the recoil atomic energy spectra after irradiation with different particles in the embodiments of the present invention. Detailed Implementation

[0018] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0019] It should be noted that the flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0020] like Figure 1 As shown, this invention proposes a method for evaluating neutron irradiation embrittlement of metallic materials based on ion irradiation, comprising the following steps: S1. The metallic materials are processed separately to prepare hardness test specimens, tensile test specimens and Charpy impact test specimens.

[0021] Metallic materials include alloys and pure metals. Alloys include steel materials, and steel materials include reactor pressure vessel (RPV) steel. RPV steel grades include A508-3, 16MND5, A533B, etc.

[0022] The sample preparation process for hardness test specimens includes: processing and polishing the metal specimen. First, the metal material is processed into thin, square sheet-like specimens, with a length and width both ≥5mm and a thickness ≥0.5mm. Then, polishing is performed, including both coarse and fine polishing. Coarse polishing uses 200-2000 mesh silicon carbide sandpaper; for example, multiple sheets of silicon carbide sandpaper with increasing mesh size can be used sequentially. Fine polishing uses silk impregnated with diamond powder with a particle size of 0.1-0.5μm. Specifically, the silicon carbide sandpaper can be 200, 500, 1000, 1500, or 2000 mesh, etc., and the diamond powder can have a particle size of 0.1μm, 0.25μm, 0.3μm, 0.4μm, or 0.5μm, etc. Understandably, the shape and size of the specimen can be selected according to actual needs, facilitating irradiation embrittlement assessment.

[0023] The preparation process for tensile and Charpy impact specimens includes: processing the metal material according to standard ASTM E8 / 8M, followed by polishing to prepare standard tensile specimens; and processing the metal material according to standard ASTM E23, followed by polishing to prepare Charpy impact specimens. The specific methods and parameters for polishing the tensile and Charpy impact specimens are not limited, but the surface roughness of both polished specimens must be less than 0.2 μm.

[0024] S2. Neutron irradiation was applied to the hardness test specimens, tensile test specimens, and Charpy impact test specimens. Heavy ion irradiation was applied to the hardness test specimens to determine the irradiation damage amount and irradiation damage rate.

[0025] In step S2, the neutron irradiation temperature is 290℃±15℃, and the neutron irradiation dose includes at least two doses, with a total neutron irradiation dose of 1×10⁻⁶. 19 n / cm 2 ~1.2×10 20 n / cm 2 Neutron energy > 1 MeV; according to 1 dpa = 1 × 10 21 n / cm 2 The neutron irradiation damage amount (in dpa) of the hardness sample is calculated and determined. Then, the neutron irradiation damage rate (in dpa / s) of the hardness sample is calculated by dividing the total irradiation damage amount by the irradiation time.

[0026] Specifically, the neutron irradiation temperature can be selected from 275℃, 285℃, 290℃, 295℃, or 305℃, etc., and the neutron irradiation dose can include two, three, four, five, six, etc., with a neutron irradiation dose of 1×10⁻⁶. 19 n / cm 2 5×10 19 n / cm 2 7×1019 n / cm 2 1×10 20 n / cm 2 Or 1.2×10 20 n / cm 2 wait.

[0027] In step S2, the heavy ion irradiation temperature is the same as the neutron irradiation temperature. The heavy ions include at least two of the following: iron ions, carbon ions, nickel ions, and manganese ions. The irradiation dose for each type of heavy ion includes at least three doses, and the irradiation dose is 1 × 10⁻⁶. 13 ions / cm 2 ~1×10 18 ions / cm 2 The irradiation energy of each heavy ion includes at least 10 types, with an irradiation energy ≥ 5 MeV / u (u is the number of nucleons); the heavy ion irradiation damage rate (in dpa / s) and heavy ion irradiation damage amount (in dpa) are calculated for each heavy ion, and the irradiation damage amount of at least one heavy ion is equal to the neutron irradiation damage amount. The heavy ion irradiation damage amount is the average value of the damage amounts of heavy ions with different irradiation energies.

[0028] Specifically, the heavy ion irradiation temperature can also be selected from 275℃, 285℃, 290℃, 295℃ or 305℃, etc.; heavy ions can include iron ions and carbon ions, or iron ions and nickel ions, or carbon ions and manganese ions, etc.

[0029] The heavy ions used in heavy ion irradiation must be selected based on the irradiation capacity of the heavy ion irradiation equipment and the composition of the metal material. In some embodiments, the metal material is steel, and the heavy ions can be carbon ions and iron ions. Carbon and iron are constituent elements of steel (especially iron), and the heavy ion irradiation equipment can meet the irradiation requirements, making it relatively easy to implement. Furthermore, the higher the element number, the shorter the time required to achieve the required irradiation damage (irradiation dose), thus saving irradiation time.

[0030] The irradiation dose for each heavy ion can include three, four, five, etc., and the irradiation dose can be selected as 1×10. 13 ions / cm 2 2.7×10 15 ions / cm 2 3.7×10 15 ions / cm 2 2.7×10 16 ions / cm 2 Or 1×10 18 ions / cm 2 wait.

[0031] The irradiation energy for each type of heavy ion can include 10, 15, or 20 types, etc. The irradiation energy for heavy ions needs to be ≥5 MeV / u. For example, for... 56 For Fe, with a nucleon number u of 56, the irradiation energy of iron ions needs to be ≥5×56=280MeV, i.e., ≥280MeV. In some embodiments, a gradient energy reduction device is used to change the energy of each heavy ion, thereby achieving the irradiation damage distribution of multiple heavy ion irradiation energies in the metal sample.

[0032] Based on the selected heavy ion irradiation dose, the heavy ion irradiation damage was calculated using the Monte Carlo simulation program SRIM. The average value of the heavy ion irradiation damage distribution curves at different irradiation energies was determined by superimposing these curves; this average value represents the heavy ion irradiation damage of the hardness sample. The heavy ion irradiation damage rate of the hardness sample was calculated by dividing the total heavy ion irradiation damage by the irradiation time. Heavy ion irradiation was achieved using a heavy ion accelerator. The irradiation damage was determined based on the selected irradiation dose and energy. The irradiation time was the time required for the heavy ion accelerator to deliver the selected irradiation dose; that is, the irradiation time could be determined based on the parameters of different accelerators (heavy ion beam intensity, in ions / cm²). 2 Adjustments are made to determine the heavy ion irradiation damage rate of the hardness sample. Therefore, the heavy ion irradiation damage rate can be determined before irradiation based on the irradiation dose, irradiation energy, and selected heavy ion accelerator parameters. By selecting different heavy ion accelerators or adjusting certain accelerator parameters, the heavy ion irradiation time can be adjusted, thereby adjusting the heavy ion irradiation damage rate.

[0033] Since this invention selects a heavy ion irradiation energy ≥ 5 MeV / u, under this energy condition, the heavy ion irradiation damage rate generally does not exceed 5 × 10⁻⁶. -4 dpa / s, the mainstream parameter is around 10 -6 The damage rate is around dpa / s, but varies considerably among different heavy ion irradiation devices. The heavy ion irradiation damage rate applicable to this invention is 5 × 10⁻⁶. -8 dpa / s ~5×10 -4 dpa / s, this range already covers the damage rate range of existing mainstream heavy ion accelerators.

[0034] Heavy ion irradiation utilizes high-energy heavy ions generated by an accelerator to irradiate metallic materials (such as RPV steel). It can achieve the equivalent of several years of neutron irradiation in just a few hours, significantly improving the efficiency of irradiation damage assessment experiments. Furthermore, compared to neutron irradiation, heavy ion irradiation offers advantages such as lower experimental costs and easier adjustment of irradiation conditions (e.g., irradiation dose rate, irradiation temperature), making it an effective method for analyzing neutron irradiation damage in RPV steel and evaluating its irradiation performance.

[0035] S3. Measure the hardness of the hardness test specimens before and after irradiation, and calculate the first yield strength increment after neutron irradiation and the second yield strength increment after heavy ion irradiation; conduct tensile tests on the tensile test specimens before and after irradiation to obtain the third yield strength increment after neutron irradiation; conduct Charpy impact tests on the Charpy impact test specimens before and after irradiation to obtain the irradiation embrittlement transition temperature increment after neutron irradiation.

[0036] In step S3, the Vickers hardness of the hardness samples before and after irradiation is measured to obtain the Vickers hardness increments after neutron irradiation and heavy ion irradiation, respectively. Vickers hardness measurements are performed using a Vickers hardness tester, with at least 5 measurements taken, and the average value is taken as the final Vickers hardness. The Vickers hardness increment ΔH (in kgf / mm²) caused by irradiation is calculated using the Vickers hardening change before and after irradiation. 2 ).

[0037] Furthermore, the first yield strength increment (in MPa) and the second yield strength increment (in MPa) are calculated using equations (1) and (2), respectively. Equations (1) and (2) are expressed as follows: Δσ y1 =3.06ΔH1 (1) Δσ y2 =3.06ΔH2 (2) Where, Δσ y1 ΔH1 represents the first yield strength increment, and Δσ represents the Vickers hardness increment after neutron irradiation. y2 ΔH2 represents the second yield strength increment, and ΔH2 represents the Vickers hardness increment after heavy ion irradiation.

[0038] It should be noted that in equations (1) and (2), the conversion coefficient between the yield strength increment and the Vickers hardness increment is 3.06, which applies to RPV steel (grades A508-3, 16MND5, A533B). This material belongs to the MnMoNi series low alloy steel and is processed by forging. The heat treatment process of the material is normal tempering + quenching and tempering. The elemental composition and content range of the material are shown in Table 1.

[0039] Table 1. Composition and content of materials In step S3, tensile tests are performed on tensile specimens before and after neutron irradiation according to standard ASTM E8 / 8M. The yield strength of the tensile specimens before and after irradiation is measured, and the third yield strength increment Δσ after neutron irradiation is calculated. y n (Unit: MPa). Charpy impact tests were conducted on Charpy impact specimens before and after neutron irradiation according to standard ASTM E23 to determine the irradiation embrittlement transition temperature increment ΔT after neutron irradiation. n(Unit: °C)

[0040] S4. Establish the first relationship between the first yield strength increment and the neutron irradiation damage, the second relationship between the second yield strength increment and the heavy ion irradiation damage, and the third relationship between the third yield strength increment and the irradiation embrittlement transition temperature increment.

[0041] According to relevant irradiation performance studies, the yield strength increment Δσ after irradiation is... y The radiation damage amount D generally exhibits an exponential relationship, therefore the basic model Δσ is adopted. y =A×D B Fit the yield strength increment Δσ after neutron irradiation and heavy ion irradiation respectively. y The correlation formula between the radiation damage amount D (independent variable) and the actual radiation damage is given, where the fitting coefficients A and B need to be determined based on the specific data. Specifically, the first yield strength increment Δσ calculated in step S3 is... y1 By fitting the neutron irradiation damage amount, the first fitting coefficient A1 and the power exponent B of the neutron irradiation damage amount are determined. n Establish the first relationship. The second yield strength increment Δσ calculated in step S3 is then used. y2 By fitting the heavy ion irradiation damage to the model, the second fitting coefficient A2 and the power exponent B of the heavy ion irradiation damage were determined. i Establish a second relation.

[0042] The first relation is shown in equation (3): (3) Where, Δσ y1 ' is the first yield strength increment, A1 is the first fitting coefficient, D1 is the neutron irradiation damage, B n This is the power exponent of the neutron irradiation damage.

[0043] The second relation is shown in equation (4): (4) Where, Δσ y2 ' is the second yield strength increment, A2 is the second fitting coefficient, D2 is the heavy ion irradiation damage, B i It represents the power exponent of the damage caused by heavy ion irradiation.

[0044] Since heavy ion irradiation uses at least two types of heavy ions, the second relationship mentioned above also includes at least two; correspondingly, A2 and B... i All have at least two, at least two B i Let them be labeled B. i 1. B i 2nd grade.

[0045] Furthermore, according to the basic theory of irradiation properties of low alloy steel, Δσ y n With ΔT n The relationship is directly proportional, increasing the third yield strength increment Δσ in step S3. y n With the increase in irradiation embrittlement transition temperature ΔT n Perform linear fitting, determine the linear fitting coefficients, and establish the third relationship as shown in equation (5): ΔT n =p×Δσ y n (5) Where, ΔT n Δσ represents the irradiation embrittlement transition temperature increment after neutron irradiation, p is the linear fitting coefficient, and Δσ is the linear embrittlement transition temperature increment. y This represents the third yield strength increment.

[0046] S5. Based on step S4, and combining the irradiation damage amount, irradiation damage rate, and average recoil atom energy of neutrons and heavy ions, establish the irradiation embrittlement correlation formula, and calculate the irradiation embrittlement transition temperature increment value according to the irradiation embrittlement correlation formula. Step S5 includes the following sub-steps: S5.1. The power exponents of the first and second relations are uniformly corrected, and radiation hardening correlations are established by combining the first yield strength increment, the second yield strength increment, the average energy of the recoil atoms of neutrons and heavy ions, the irradiation damage rate, and the irradiation damage amount.

[0047] Preferably, step S5.1 includes the following sub-steps: S5.1.1. Use formula (6) to standardize and correct the power exponent and establish the first hardened correlation.

[0048] Equation (6) is expressed as follows: b=(B n +(B i 1+ B i 2+…B i x ) / x) / 2 (6) Where b is the power exponent of the unified correction, B n B is the power exponent of neutron irradiation damage. i denoted by the power exponent of heavy ion irradiation damage, x represents the number of heavy ion species. Understandably, B i 1 represents the power exponent of the radiation damage caused by the first heavy ion, and B i 2 represents the power exponent of the radiation damage caused by the second heavy ion, B i x denoted as the power exponent of the radiation damage caused by the x-th heavy ion.

[0049] Furthermore, according to relevant research, the basic principle can be learned: in low-Cu (Cu content ≤ 0.08 wt%) RPV steel, Δσ y It exhibits a linear relationship with lgφ (where φ is the irradiation damage rate). Based on this conclusion, a direct proportional relationship Δσ is established by introducing a fitting coefficient C. y ∝lg(C×φ).

[0050] Based on the basic model Δσ y =A×D B And the unified correction of the power exponent b, introducing the effect of irradiation damage rate φ on irradiation hardening Δσ y ∝lg(C1×φ), and based on the previously calculated first yield strength increment Δσ y1 and the corresponding neutron irradiation damage, and the previously calculated second yield strength increment Δσ y2 The third fitting coefficient A3 and the first correlation coefficient C1 are determined based on the corresponding heavy ion irradiation damage amount, thereby establishing the first hardening correlation between neutron irradiation and heavy ion irradiation. The independent variables include irradiation damage amount D and irradiation damage rate φ.

[0051] The first hardening correlation is shown in equation (7): Δσ y =A3×k1×D b (7) Where, Δσ y For yield strength increment, A3 is the third fitting coefficient, k1 is the first correlation factor, D is the irradiation damage amount, and b is the power exponent of the unified correction; the expression for k1 is k1=lg(C1×φ), where C1 is the first correlation coefficient and φ is the irradiation damage rate.

[0052] Through the basic model Δσ y =A×D B Based on this, the variable irradiation damage rate φ is introduced to increase the yield strength increment Δσ after irradiation. y The accuracy of the calculation.

[0053] S5.1.2. Based on the first hardening correlation, calculate the first difference between the normalized yield strength increment after neutron irradiation and heavy ion irradiation. The normalized yield strength increment is Δσ. y / k1; If the first difference is ≤5, the first hardening correlation is the irradiation hardening correlation; if the first difference is >5, calculate the average atomic recoil energy of neutrons and heavy ions, and establish the second hardening correlation, which is used as the irradiation hardening correlation.

[0054] Specifically, a normalized yield strength increment (i.e., Δσ) is established. y / k1) Using a double logarithmic coordinate curve of the irradiation damage amount D, the normalized yield strength increment after neutron irradiation is determined based on the first yield strength increment and the neutron irradiation damage rate; the normalized yield strength increment after heavy ion irradiation is determined based on the second yield strength increment and the heavy ion irradiation damage rate. The difference between these two normalized yield strength increments is the first difference. The magnitude of the first difference is then determined. If the first difference is ≤ 5, the final irradiation hardening correlation formula is the aforementioned first hardening correlation formula.

[0055] Based on the theory of irradiation damage, the defect parameters (size d, number density N) generated by irradiation are related to lgT. 1 / 2 They are directly proportional, i.e., N∝lgT 1 / 2 ,d∝lgT 1 / 2 (T) 1 / 2 (where Δσ is the average energy of the recoil atoms); according to the theory of dispersion strengthening, Δσ y The relationship between Δσ and the number density N and size d of irradiated defects is present. y ∝N 1 / 2 d 1 / 2 Based on the above relationships, a direct proportional relationship Δσ is established by introducing the fitting coefficient E. y ∝lg 1 / 2 (E×T 1 / 2 ).

[0056] If the first difference is greater than 5, then the average energy T of the recoil atoms needs to be introduced. 1 / 2 The effect of (unit: eV) on radiation hardening Δσ y ∝lg 1 / 2 (E×T 1 / 2 ), and based on the aforementioned calculated first yield strength increment Δσ y1 and the corresponding neutron irradiation damage amount and neutron irradiation damage rate, and the previously calculated second yield strength increment Δσ y2 Based on the corresponding heavy ion irradiation damage amount and heavy ion irradiation damage rate, the fourth fitting coefficient A4, the second correlation coefficient C2, the third correlation coefficient E, and the power exponent b' of the irradiation damage amount were determined, thereby establishing the second hardening correlation formula that links neutron irradiation and heavy ion irradiation. The independent variables include the irradiation damage amount D, the irradiation damage rate φ, and the average energy T of the recoil atoms. 1 / 2 .

[0057] Among them, the average energy T of the recoil atom 1 / 2 The average recoil atom energy of neutrons and heavy ions under different irradiation parameters was calculated by inputting parameters of neutrons and heavy ions (particle type, energy), the dislocation threshold energy of material elements, material density, defect generation model, etc. The method for calculating the average recoil atom energy is existing technology and will not be elaborated here.

[0058] Based on the second hardening correlation, establish a re-normalized yield strength increment (i.e., Δσ). y / k2, k2=lg(C2×φ)×lg 1 / 2 (E×T 1 / 2 )) The second difference between the normalized yield strength increment after neutron irradiation and heavy ion irradiation is calculated from the double logarithmic coordinate curve of the irradiation damage amount D. The power exponent in equation (8) is adjusted until the second difference is ≤5, thereby determining the power exponent b' of the final irradiation damage amount.

[0059] Specifically, the normalized yield strength increment after neutron irradiation is determined based on the first yield strength increment, the neutron irradiation damage rate, and the average energy of the recoil atoms of neutrons; the normalized yield strength increment after heavy ion irradiation is determined based on the second yield strength increment, the heavy ion irradiation damage rate, and the average energy of the recoil atoms of heavy ions. The difference between the two normalized yield strength increments is the second difference.

[0060] The second hardening correlation is shown in equation (8): Δσ y =A4×k2×D b’ (8) Where, Δσ y The yield strength increment is represented by A4, the fourth fitting coefficient is k2, the second correlation factor is D, the irradiation damage is D, and b' is the power exponent for further correction. The expression for k2 is k2 = lg(C2 × φ) × lg 1 / 2 (E×T 1 / 2 C2 is the second correlation coefficient, φ is the irradiation damage rate, E is the third correlation coefficient, and T is the third correlation coefficient. 1 / 2 This is the average energy of the recoil atom.

[0061] By further introducing the variable average energy T of the recoil atom based on equation (7) 1 / 2 This increases the yield strength increment Δσ after irradiation. y The accuracy of the calculation.

[0062] S5.2. Based on the radiation hardening correlation and the linear fitting coefficient of the third relation, establish the radiation embrittlement correlation and calculate the radiation embrittlement transition temperature increment value according to the radiation embrittlement correlation.

[0063] In some embodiments, the irradiation hardening correlation is the first hardening correlation, i.e., equation (7), combined with the third relation, i.e., equation (5), then the irradiation embrittlement correlation is as shown in equation (9): ΔT=A3×p×k1×D b (9) Where ΔT is the irradiation embrittlement transition temperature increment, A3 is the third fitting coefficient, k1 is the first correlation factor, D is the irradiation damage amount, and b is the power exponent of the unified correction; the expression for k1 is k1=lg(C1×φ), where C1 is the first correlation coefficient and φ is the irradiation damage rate.

[0064] In other embodiments, the irradiation hardening correlation is the second hardening correlation, i.e., equation (8), combined with the third relation, i.e., equation (5), the irradiation embrittlement correlation is as shown in equation (10): ΔT=A4×p×k2×D b’ (10) Where ΔT is the irradiation embrittlement transition temperature increment, A4 is the fourth fitting coefficient, p is the linear fitting coefficient, k2 is the second correlation factor, D is the irradiation damage amount, and b' is the power exponent for further correction; the expression for k2 is k2=lg(C2×φ)×lg 1 / 2 (E×T 1 / 2 C2 is the second correlation coefficient, φ is the irradiation damage rate, E is the third correlation coefficient, and T is the third correlation coefficient. 1 / 2 This is the average energy of the recoil atom.

[0065] Based on the above correlation formula for irradiation embrittlement, by inputting the irradiation damage amount D, irradiation damage rate φ, and average recoil atom energy T... 1 / 2 This allows for the calculation of the irradiation embrittlement transition temperature increment of metallic materials, in order to assess the neutron irradiation embrittlement level of metallic materials (such as RPV steel).

[0066] This innovative correlation incorporates irradiation damage, irradiation damage rate, and average recoil atom energy into the correlation model, making the correlation more scientific and reasonable. This allows for the simulation of neutron irradiation by heavy-ion irradiation to assess the mechanical properties of metallic materials, enabling a more accurate evaluation of the embrittlement behavior of metallic materials under neutron irradiation. Based on the correlation results, the heavy-ion irradiation parameters of metallic materials can be used to assess or predict the embrittlement level under neutron irradiation conditions, thereby achieving an accurate assessment of the embrittlement risk of metallic materials (RPV steel) during service.

[0067] The neutron-heavy irradiation correlation model of this invention not only uses irradiation damage as a key parameter, but also considers the differences in the energy spectrum and irradiation damage rate of primary ex-situ atoms under different particle irradiation conditions. It introduces irradiation damage rate and average recoil atom energy as key physical parameters. These two parameters differ by orders of magnitude between ion and neutron irradiation, and have a decisive influence on defect evolution and the final embrittlement effect. The irradiation embrittlement correlation formula proposed in this invention simultaneously considers irradiation damage, irradiation damage rate, and average recoil atom energy, solving the problem of low accuracy in embrittlement assessment caused by the single parameter in existing neutron-ion irradiation correlation factors. It achieves accurate correlation of embrittlement data under neutron and heavy ion irradiation, providing strong technical support for the irradiation embrittlement assessment of metallic materials such as RPV steel.

[0068] This invention proposes a correlation formula between neutron irradiation and heavy ion irradiation that simultaneously considers irradiation damage amount, irradiation damage rate, and average energy of recoil atoms, and establishes an assessment method for neutron irradiation embrittlement of metallic materials based on ion irradiation, bringing several significant benefits: From the perspective of correlation accuracy, this evaluation method innovatively utilizes a neutron-ion irradiation correlation factor to propose an evaluation method for neutron irradiation embrittlement of metallic materials based on ion irradiation. Compared with the traditional method of measuring the irradiation embrittlement transition temperature increment (ΔT), this improvement is groundbreaking. Traditional methods for irradiation embrittlement evaluation require multiple Charpy impact tests, resulting in extremely high sample consumption and making it impossible to achieve irradiation embrittlement evaluation based on ion irradiation. Furthermore, the traditional neutron-ion irradiation correlation factor ignores the influence of irradiation damage rate and the average energy of recoil atoms on irradiation damage, leading to significant errors in the neutron-ion irradiation correlation. In contrast, this invention, by comprehensively considering the two key factors of irradiation damage rate and the average energy of recoil atoms, can more accurately derive the irradiation embrittlement transition temperature increment ΔT of RPV steel under neutron irradiation from ion irradiation data. This provides reliable data support for the accurate evaluation of the service performance of RPV steel and facilitates the low-cost evaluation of expensive neutron irradiation embrittlement using ion irradiation methods.

[0069] In terms of evaluation efficiency, this invention utilizes a neutron-ion irradiation correlation factor to replace part of the neutron irradiation experiment with ion irradiation experiments in the actual irradiation embrittlement assessment process. Since neutron irradiation experiments have extremely long cycles while ion irradiation experiments have short cycles, combining the two significantly reduces the assessment cycle and neutron irradiation cost for RPV steel, and also reduces the neutron irradiation dose for technicians. This efficient and low-cost assessment method greatly facilitates the research and engineering application of RPV steel and contributes to the rapid development of the nuclear power materials field.

[0070] From an engineering practicality perspective, the evaluation method of this invention is highly targeted at assessing the irradiation embrittlement of metallic materials such as RPV steel. This method can be directly applied to the time-limited aging analysis of RPV, providing core data (initial transformation temperature T0 + embrittlement transformation temperature increment ΔT after irradiation ≤ 93℃) for RPV aging management, periodic safety reviews, and life extension demonstrations. It provides core information for subsequent assessment of RPV safety and meets the needs of practical engineering and safety reviews.

[0071] In terms of RPV life management, the assessment method of neutron irradiation embrittlement of metallic materials based on ion irradiation can predict the performance of RPV in the later stage of service, provide basic data support for long-term asset management and decision-making on major issues of nuclear power plants, and ensure the safe and stable operation of nuclear reactors.

[0072] The following examples illustrate this: The neutron irradiation embrittlement assessment method for metallic materials based on ion irradiation of the present invention was used to assess the neutron irradiation embrittlement of RPV steel, such as... Figure 1 As shown, the evaluation method includes the following steps: S1. The metallic materials are processed separately to prepare hardness test specimens, tensile test specimens and Charpy impact test specimens.

[0073] The metal material is RPV steel with grade A508-3.

[0074] The sample preparation process for hardness test specimens includes: processing and polishing the metal specimens. First, the metal material is processed into thin square specimens with a length of 10 mm, a width of 10 mm, and a thickness of 1 mm. Then, coarse polishing is performed sequentially using 200-mesh, 1200-mesh, and 2000-mesh silicon carbide sandpaper. Finally, fine polishing is performed using silk impregnated with diamond powder with a particle size of 0.25 μm.

[0075] The preparation process for tensile and Charpy impact specimens includes: machining the metal material according to standard ASTM E8 / 8M, followed by polishing to prepare standard tensile specimens; and machining the metal material according to standard ASTM E23, followed by polishing to prepare Charpy impact specimens. The surface roughness of both tensile and Charpy impact specimens is less than 0.2 μm.

[0076] S2. Neutron irradiation was applied to the hardness test specimens, tensile test specimens, and Charpy impact test specimens. Heavy ion irradiation was applied to the hardness test specimens to determine the irradiation damage amount and irradiation damage rate.

[0077] In step S2, the neutron irradiation temperature is 290℃, and the neutron irradiation dose includes 5×10⁻⁶ ppm. 19 n / cm 2 and 1×10 20 n / cm 2A total of 2 neutron irradiation doses were administered, with neutron energies > 1 MeV; according to 1 dpa = 1 × 10⁻⁶ 21 n / cm 2 The neutron irradiation damage amounts of the hardness test specimens were calculated to be 0.05 dPa and 0.1 dPa, and the neutron irradiation damage rate of the hardness test specimens was 7.8 × 10⁻⁶. - 9 dpa / s.

[0078] In step S2, during heavy ion irradiation, the irradiation temperature is 290℃, and the heavy ions include iron ions and carbon ions. The C ion energy is 84 MeV, and the total irradiation dose is 4; the Fe ion energy is 352 MeV, and the irradiation dose includes 2.7 × 10⁻⁶ ions. 15 ions / cm 2 5.4×10 15 ions / cm 2 2.7×10 16 ions / cm 2 A total of three irradiation doses were administered. A gradient energy reduction device was used to vary the injection energy of carbon and iron ions. By combining different combinations of energy reduction disk thicknesses, a total of 20 heavy ion irradiation energies were used to achieve irradiation damage distributions (e.g., ...). Figure 2 As shown), according to Figure 2 It is evident that different heavy ion irradiation energies lead to differences in the depth of irradiation damage.

[0079] Based on the selected heavy ion irradiation dose, the heavy ion irradiation damage was calculated using the Monte Carlo simulation program SRIM. Based on the superposition of irradiation damage distribution curves for the aforementioned 20 heavy ion irradiation energies, the irradiation damage amounts for iron and carbon ions were determined, and the irradiation damage rates were calculated. The calculated irradiation damage amounts for iron ions were 0.15 dPa, 0.3 dPa, and 1.5 dPa, respectively, while those for carbon ions were 0.05 dPa, 0.1 dPa, 0.15 dPa, and 0.3 dPa, respectively. The irradiation damage rate for iron ions was 5.6 × 10⁻⁶. -6 At dpa / s, the irradiation damage rate of carbon ions is 2.7 × 10⁻⁶. -6 dpa / s.

[0080] S3. Measure the hardness of the hardness test specimens before and after irradiation, and calculate the first yield strength increment after neutron irradiation and the second yield strength increment after heavy ion irradiation; conduct tensile tests on the tensile test specimens before and after irradiation to obtain the third yield strength increment after neutron irradiation; conduct Charpy impact tests on the Charpy impact test specimens before and after irradiation to obtain the irradiation embrittlement transition temperature increment after neutron irradiation.

[0081] In step S3, the Vickers hardness of the hardness samples before and after irradiation is measured. Five measurements are taken using a Vickers hardness tester, and the average value is taken as the final Vickers hardness. The Vickers hardness increments after neutron irradiation and heavy ion irradiation are obtained respectively. The Vickers hardness increment ΔH caused by irradiation is determined by calculating the Vickers hardness change before and after irradiation. Then, the first yield strength increment and the second yield strength increment are calculated using equations (1) and (2) respectively. Equations (1) and (2) are expressed as follows: Δσ y1 =3.06ΔH1 (1) Δσ y2 =3.06ΔH2 (2) Where, Δσ y1 ΔH1 represents the first yield strength increment, and Δσ represents the Vickers hardness increment after neutron irradiation. y2 ΔH2 represents the second yield strength increment, and ΔH2 represents the Vickers hardness increment after heavy ion irradiation.

[0082] In step S3, tensile tests are performed on tensile specimens before and after neutron irradiation according to standard ASTM E8 / 8M. The yield strength of the tensile specimens before and after irradiation is measured, and the third yield strength increment Δσ after neutron irradiation is calculated. y n Charpy impact tests were conducted on Charpy impact specimens before and after neutron irradiation according to standard ASTM E23 to determine the increase in irradiation embrittlement transition temperature ΔT after neutron irradiation. n .

[0083] S4. Establish the first relationship between the first yield strength increment and the neutron irradiation damage, the second relationship between the second yield strength increment and the heavy ion irradiation damage, and the third relationship between the third yield strength increment and the irradiation embrittlement transition temperature increment.

[0084] Specifically, the first yield strength increment Δσ calculated in step S3 is... y1 By fitting the neutron irradiation damage amount, a relationship Δσ between the yield strength increment after neutron irradiation and the neutron irradiation damage amount is established. y =220.9×D 0.42 That is, the first relation. The second yield strength increment Δσ calculated in step S3... y2 By fitting the corresponding heavy ion irradiation damage amount, a second relationship is established, including the relationship between the yield strength increment after carbon ion irradiation and the carbon ion irradiation damage amount Δσ. y =179.4×D 0.49 The relationship between the increase in yield strength after iron ion irradiation and the amount of iron ion irradiation damage is expressed as Δσ. y =128.7×D 0.45 .like Figure 3The figure shows the relationship between irradiation damage and yield strength increment of metallic materials after neutron irradiation and heavy ion irradiation. The third yield strength increment Δσ from step S3 is also shown. y n With the increase in irradiation embrittlement transition temperature ΔT n Perform linear fitting and establish ΔT n =0.51×Δσ y n That is, the third relation, such as Figure 4 As shown.

[0085] S5. Based on step S4, and combining the irradiation damage amount, irradiation damage rate, and average recoil atom energy of neutrons and heavy ions, establish the irradiation embrittlement correlation formula, and calculate the irradiation embrittlement transition temperature increment value according to the irradiation embrittlement correlation formula. Step S5 includes the following sub-steps: S5.1 Establish the irradiation hardening correlation. Step S5.1 includes the following sub-steps: S5.1.1 The power exponents of the first and second relations are uniformly corrected. The uniformly corrected power exponent b = (0.42 + (0.49 + 0.45) / 2) / 2 ≈ 0.44. Furthermore, the effect of irradiation damage rate φ on irradiation hardening Δσ is introduced. y ∝lg(C1×φ), and based on the previously calculated first yield strength increment Δσ y1 and the corresponding neutron irradiation damage, and the previously calculated second yield strength increment Δσ y2 And the corresponding heavy ion irradiation damage, establishing the first hardening correlation relating neutron irradiation and heavy ion irradiation, Δσ y =-36.0×lg(53.7×φ)×D 0.44 The independent variables include the amount of irradiation damage D and the irradiation damage rate φ.

[0086] S5.1.2 Establish the normalized yield strength increment (i.e., Δσ) y / k1) is a log-log plot of the radiation damage amount D, as shown in the figure. Figure 5 As shown. It was determined that the first difference between the normalized yield strength increment after neutron irradiation and heavy ion irradiation was >5, therefore, the average energy T of the recoil atoms was introduced. 1 / 2 Effect of radiation hardening Δσ y ∝lg 1 / 2 (E×T 1 / 2 The Monte Carlo simulation program Geant4 was used, with input parameters for neutrons, carbon ions, and iron ions (irradiation energy of carbon ions: 84 MeV, irradiation energy of iron ions: 352 MeV, irradiation energy of neutrons: 1 MeV), the displacement threshold energy of the alloying elements in the A508-3 material (40 eV), and the density of the A508-3 material (7.8 g / cm³).2 Using models such as NRT, the average energy of recoil atoms for different particles (10 for neutrons) was calculated. 4 eV, carbon ion is 10 eV 2 eV, iron ions are 10 4 eV).

[0087] Furthermore, based on the above-calculated average recoil atomic energies of neutrons, carbon ions, and iron ions, and combined with the previously calculated first yield strength increment Δσ... y1 and the corresponding neutron irradiation damage amount and neutron irradiation damage rate, and the previously calculated second yield strength increment Δσ y2 The corresponding heavy ion irradiation damage amount and heavy ion irradiation damage rate are fitted to establish a renormalized yield strength increment (i.e., Δσ). y / k2, k2=lg(C2×φ)×lg 1 / 2 (E×T 1 / 2 The double logarithmic coordinate curve of the radiation damage amount D (e.g.) Figure 6 As shown), calculate the second difference between the normalized yield strength increment after neutron irradiation and heavy ion irradiation, adjust the power exponent of the irradiation damage amount until the second difference is ≤5, thereby determining the power exponent b' for further correction, and establish the second hardening correlation as shown in equation (11). The independent variables include the irradiation damage amount D, the irradiation damage rate φ, and the average energy T of the recoil atoms. 1 / 2 Equation (11) is expressed as follows: Δσ y =52.7×k2×D 0.5 (11) Where, Δσ y Let k2 be the yield strength increment after irradiation, k2 be the second correlation factor, and D be the irradiation damage. The expression for k2 is k2 = -lg(1.26 × 10⁻⁶). 3 ×φ)×lg 1 / 2 (3×10 5 ×T 1 / 2 ), φ is the irradiation damage rate, T 1 / 2 This is the average energy of the recoil atom.

[0088] S5.2. Based on the irradiation hardening correlation (i.e., the second hardening correlation), combined with the third relationship, and with a linear fitting coefficient p=0.51, the irradiation embrittlement correlation is established as shown in equation (12). The irradiation embrittlement transition temperature increment is calculated according to the irradiation embrittlement correlation, and equation (12) is expressed as follows: ΔT = -26.877 × lg(1.26 × 10) 3 ×φ)×lg 1 / 2 (3×10 5 ×T 1 / 2 )×D 0.5(12) Where ΔT is the irradiation embrittlement transition temperature increment, φ is the irradiation damage rate, and T 1 / 2 Where is the average energy of the recoil atoms, and D is the amount of irradiation damage.

[0089] Based on the above correlation formula for irradiation embrittlement, by inputting the irradiation damage amount D, irradiation damage rate φ, and average recoil atom energy T... 1 / 2 This allows for the assessment of the neutron irradiation embrittlement level of RPV steel (the increment of the irradiation embrittlement transition temperature). For example, when RPV steel (A508-3 steel) is irradiated with 60 MeV carbon ions, the irradiation damage amount D = 0.09 dpa, and the irradiation damage rate φ = 2 × 10⁻⁶. -6 dpa / s, according to Figure 7 The recoil atom energy spectrum (recoil energy-integral spectrum) yields the average energy T of the recoil atoms irradiated with carbon ions. 1 / 2 =400eV, then the irradiation embrittlement transition temperature increment ΔT after 0.09dpa of RPV service is 59.6℃.

[0090] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for evaluating neutron irradiation embrittlement of metallic materials based on ion irradiation, characterized in that, Includes the following steps: S1. The metallic materials are processed separately to prepare hardness test specimens, tensile test specimens and Charpy impact test specimens. S2. The hardness test specimen, the tensile test specimen, and the Charpy impact test specimen are subjected to neutron irradiation, and the hardness test specimen is subjected to heavy ion irradiation to determine the irradiation damage amount and irradiation damage rate. S3. Measure the hardness of the hardness test specimens before and after irradiation, and calculate the first yield strength increment after neutron irradiation and the second yield strength increment after heavy ion irradiation; perform a tensile test on the tensile test specimens before and after irradiation to obtain the third yield strength increment after neutron irradiation; perform a Charpy impact test on the Charpy impact test specimens before and after irradiation to obtain the irradiation embrittlement transition temperature increment after neutron irradiation. S4. Establish a first relationship between the first yield strength increment and the neutron irradiation damage amount, a second relationship between the second yield strength increment and the heavy ion irradiation damage amount, and a third relationship between the third yield strength increment and the irradiation embrittlement transition temperature increment. S5. Based on step S4, and combining the irradiation damage amount, the irradiation damage rate, and the average energy of the recoil atoms of neutrons and heavy ions, establish the irradiation embrittlement correlation formula, and calculate the irradiation embrittlement transition temperature increment value according to the irradiation embrittlement correlation formula.

2. The method for evaluating neutron irradiation embrittlement of metallic materials based on ion irradiation according to claim 1, characterized in that, In step S1, the hardness sample is processed and polished. The polishing process includes coarse polishing and fine polishing. The coarse polishing uses 200-2000 mesh silicon carbide sandpaper, and the fine polishing uses silk impregnated with diamond powder with a particle size of 0.1-0.5 μm; and / or, The roughness of both the tensile specimen and the Charpy impact specimen is less than 0.2 μm.

3. The method for evaluating neutron irradiation embrittlement of metallic materials based on ion irradiation according to claim 1, characterized in that, In step S2, the neutron irradiation temperature is 290℃±15℃, and the neutron irradiation dose includes at least two doses, with a neutron irradiation dose of 1×10⁻⁶. 19 n / cm 2 ~1.2×10 20 n / cm 2 Neutron energy > 1 MeV; calculate the neutron irradiation damage amount and neutron irradiation damage rate of the hardness sample.

4. The method for evaluating neutron irradiation embrittlement of metallic materials based on ion irradiation according to claim 1, characterized in that, In step S2, the heavy ion irradiation temperature is the same as the neutron irradiation temperature. The heavy ions include at least two of the following: iron ions, carbon ions, nickel ions, and manganese ions. The irradiation dose for each heavy ion includes at least three doses, and the irradiation dose is 1 × 10⁻⁶. 13 ions / cm 2 ~1×10 18 ions / cm 2 The irradiation energy of each heavy ion includes at least 10 types, and the irradiation energy is ≥5MeV / u; the heavy ion irradiation damage rate and heavy ion irradiation damage amount of each heavy ion are calculated, and the heavy ion irradiation damage amount of at least one heavy ion is equal to the neutron irradiation damage amount, and the heavy ion irradiation damage amount is the average value of the damage amounts of heavy ions with different irradiation energies.

5. The method for evaluating neutron irradiation embrittlement of metallic materials based on ion irradiation according to claim 1, characterized in that, In step S3, the Vickers hardness of the hardness sample before and after irradiation is measured to obtain the Vickers hardness increments after neutron irradiation and heavy ion irradiation, respectively. Then, the first yield strength increment and the second yield strength increment are calculated using equations (1) and (2), respectively. Equations (1) and (2) are expressed as follows: Board y1 =3.06ΔH1 (1) Board y2 =3.06ΔH2 (2) Where, Δσ y1 ΔH1 represents the first yield strength increment, and Δσ represents the Vickers hardness increment after neutron irradiation. y2 ΔH2 represents the second yield strength increment, and ΔH2 represents the Vickers hardness increment after heavy ion irradiation.

6. The method for evaluating neutron irradiation embrittlement of metallic materials based on ion irradiation according to claim 1, characterized in that, In step S4, the first relation is as shown in equation (3): （3） Where, Δσ y1 ' is the first yield strength increment, A1 is the first fitting coefficient, D1 is the neutron irradiation damage, B n The power exponent of neutron irradiation damage; The second relation is shown in equation (4): （4） Where, Δσ y2 ' is the second yield strength increment, A2 is the second fitting coefficient, D2 is the heavy ion irradiation damage, B i The power exponent of heavy ion irradiation damage; The third relation is shown in equation (5): ΔT n =p×Δσ y n (5) Where, ΔT n Δσ represents the irradiation embrittlement transition temperature increment after neutron irradiation, p is the linear fitting coefficient, and Δσ is the linear embrittlement transition temperature increment. y This represents the third yield strength increment.

7. The method for evaluating neutron irradiation embrittlement of metallic materials based on ion irradiation according to claim 6, characterized in that, Step S5 includes the following sub-steps: S5.

1. The power exponents of the first relation and the second relation are uniformly corrected, and radiation hardening correlation is established by combining the first yield strength increment, the second yield strength increment, the average energy of the recoil atoms of neutrons and heavy ions, the irradiation damage rate and the irradiation damage amount. S5.

2. Based on the radiation hardening correlation and the linear fitting coefficient of the third relation, establish the radiation embrittlement correlation and calculate the radiation embrittlement transition temperature increment value according to the radiation embrittlement correlation.

8. The method for evaluating neutron irradiation embrittlement of metallic materials based on ion irradiation according to claim 7, characterized in that, Step S5.1 includes the following sub-steps: S5.1.

1. The power exponent is uniformly corrected using equation (6), and the first hardened correlation is established as shown in equation (7); the equation (6) is expressed as follows: b=(B n +(B i 1+ B i 2+…B i x ) / x) / 2 (6) Where b is the power exponent of the unified correction, B n B is the power exponent of neutron irradiation damage. i is the power exponent of the damage caused by heavy ion irradiation, and x is the number of heavy ion species; Equation (7) is expressed as follows: Board y =A3×k1×D b (7) Where, Δσ y For yield strength increment, A3 is the third fitting coefficient, k1 is the first correlation factor, D is the irradiation damage amount, and b is the power exponent of the unified correction; the expression for k1 is k1=lg(C1×φ), where C1 is the first correlation coefficient and φ is the irradiation damage rate.

9. The method for evaluating neutron irradiation embrittlement of metallic materials based on ion irradiation according to claim 8, characterized in that, Step S5.1 further includes the following sub-steps: S5.1.

2. Based on the first hardening correlation, calculate the first difference between the normalized yield strength increment after neutron irradiation and after heavy ion irradiation, wherein the normalized yield strength increment is Δσ. y / k1; If the first difference is ≤5, the first hardening correlation is the irradiation hardening correlation; If the first difference is >5, calculate the average atomic recoil energy of neutrons and heavy ions, and establish the second hardening correlation as shown in equation (8), the irradiation hardening correlation is the second hardening correlation. Equation (8) is expressed as follows: Board y =A4×k2×D b’ (8) Where, Δσ y The yield strength increment is represented by A4, the fourth fitting coefficient is k2, the second correlation factor is D, the irradiation damage is D, and b' is the power exponent for further correction. The expression for k2 is k2 = lg(C2 × φ) × lg 1 / 2 (E×T 1 / 2 C2 is the second correlation coefficient, φ is the irradiation damage rate, E is the third correlation coefficient, and T is the third correlation coefficient. 1 / 2 The average energy of the recoil atom; Based on the second hardening correlation, the yield strength increment is normalized again to Δσ. y / k2, calculate the second difference between the normalized yield strength increment after neutron irradiation and heavy ion irradiation, and adjust the power exponent in the above equation (8) until the second difference is ≤5.

10. The method for evaluating neutron irradiation embrittlement of metallic materials based on ion irradiation according to claim 9, characterized in that, The irradiation hardening correlation is the first hardening correlation, and the irradiation embrittlement correlation is shown in equation (9): ΔT=A3×p×k1×D b (9) Where ΔT is the irradiation embrittlement transition temperature increment, A3 is the third fitting coefficient, k1 is the first correlation factor, D is the irradiation damage amount, and b is the power exponent of the unified correction; the expression for k1 is k1=lg(C1×φ), where C1 is the first correlation coefficient and φ is the irradiation damage rate; or... The irradiation hardening correlation is the second hardening correlation, and the irradiation embrittlement correlation is shown in equation (10): ΔT=A4×p×k2×D b’ (10) Where ΔT is the irradiation embrittlement transition temperature increment, A4 is the fourth fitting coefficient, p is the linear fitting coefficient, k2 is the second correlation factor, D is the irradiation damage amount, and b' is the power exponent for further correction; the expression for k2 is k2=lg(C2×φ)×lg 1 / 2 (E×T 1 / 2 C2 is the second correlation coefficient, φ is the irradiation damage rate, E is the third correlation coefficient, and T is the third correlation coefficient. 1 / 2 This is the average energy of the recoil atom.

Images